This paper presents an educational software interface tool to analyze multilevel signal at the receiver of an optical communication system. This tool provides visualization in terms of eye-diagram and bit/symbol error rate along the symbol duration using Gaussian approximation method. Besides that, maximum Q-factors, minimum BER and corresponding threshold level are also displayed. This tool is developed using Matlab as an interface programming tool. The developed analyzer has been used to analyze 2, 4 and 8-PAM signal for an optical communication system. A commercial software known as OptiSystemâ„¢ has been used to develop and simulate the multilevel optical system. The performance of the develop analyzer has been validated with the build in analyzer of OptiSystem.DOI:http://dx.doi.org/10.11591/ijece.v2i4.1464